Piezoelectric devices alter their shape in response to an applied electric field. An electric field applied in the direction of polarization effects an expansion of the piezoelectric material in the same direction, while a voltage applied in the opposite direction of polarization will cause a contraction of the material in that same direction. Piezoelectric bending actuators, such as thermally pre-stressed bending actuators, use the "bending" action of the actuator to convert electrical energy into mechanical energy.
While the application of a voltage command signal typically functions well to actuate the piezoelectric device, there are some nonlinearities in operation of the piezoelectric actuator that are reflected in a voltage controlled system. For example, these nonlinearities may cause the actuator to not fully move to a desired position in response to a voltage control signal. Further the control signal may cause the actuator to move or change its position in an abrupt or sluggish manner that does not match the desired actuator movement profile for a particular application.
Thus, the present invention is directed to overcoming one or more of the problems set forth above.